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2a17bde930
Along the way, dismantle importlib._bootstrap._SpecMethods as it was no longer relevant and constructing the new function required partially dismantling the class anyway.
325 lines
10 KiB
Python
325 lines
10 KiB
Python
"""Abstract base classes related to import."""
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from . import _bootstrap
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from . import machinery
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try:
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import _frozen_importlib
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except ImportError as exc:
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if exc.name != '_frozen_importlib':
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raise
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_frozen_importlib = None
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import abc
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def _register(abstract_cls, *classes):
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for cls in classes:
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abstract_cls.register(cls)
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if _frozen_importlib is not None:
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frozen_cls = getattr(_frozen_importlib, cls.__name__)
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abstract_cls.register(frozen_cls)
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class Finder(metaclass=abc.ABCMeta):
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"""Legacy abstract base class for import finders.
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It may be subclassed for compatibility with legacy third party
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reimplementations of the import system. Otherwise, finder
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implementations should derive from the more specific MetaPathFinder
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or PathEntryFinder ABCs.
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"""
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@abc.abstractmethod
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def find_module(self, fullname, path=None):
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"""An abstract method that should find a module.
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The fullname is a str and the optional path is a str or None.
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Returns a Loader object or None.
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"""
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class MetaPathFinder(Finder):
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"""Abstract base class for import finders on sys.meta_path."""
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# We don't define find_spec() here since that would break
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# hasattr checks we do to support backward compatibility.
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def find_module(self, fullname, path):
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"""Return a loader for the module.
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If no module is found, return None. The fullname is a str and
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the path is a list of strings or None.
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This method is deprecated in favor of finder.find_spec(). If find_spec()
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exists then backwards-compatible functionality is provided for this
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method.
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"""
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if not hasattr(self, 'find_spec'):
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return None
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found = self.find_spec(fullname, path)
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return found.loader if found is not None else None
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def invalidate_caches(self):
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"""An optional method for clearing the finder's cache, if any.
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This method is used by importlib.invalidate_caches().
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"""
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_register(MetaPathFinder, machinery.BuiltinImporter, machinery.FrozenImporter,
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machinery.PathFinder, machinery.WindowsRegistryFinder)
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class PathEntryFinder(Finder):
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"""Abstract base class for path entry finders used by PathFinder."""
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# We don't define find_spec() here since that would break
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# hasattr checks we do to support backward compatibility.
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def find_loader(self, fullname):
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"""Return (loader, namespace portion) for the path entry.
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The fullname is a str. The namespace portion is a sequence of
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path entries contributing to part of a namespace package. The
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sequence may be empty. If loader is not None, the portion will
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be ignored.
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The portion will be discarded if another path entry finder
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locates the module as a normal module or package.
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This method is deprecated in favor of finder.find_spec(). If find_spec()
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is provided than backwards-compatible functionality is provided.
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"""
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if not hasattr(self, 'find_spec'):
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return None, []
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found = self.find_spec(fullname)
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if found is not None:
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if not found.submodule_search_locations:
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portions = []
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else:
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portions = found.submodule_search_locations
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return found.loader, portions
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else:
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return None, []
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find_module = _bootstrap._find_module_shim
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def invalidate_caches(self):
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"""An optional method for clearing the finder's cache, if any.
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This method is used by PathFinder.invalidate_caches().
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"""
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_register(PathEntryFinder, machinery.FileFinder)
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class Loader(metaclass=abc.ABCMeta):
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"""Abstract base class for import loaders."""
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def create_module(self, spec):
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"""Return a module to initialize and into which to load.
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This method should raise ImportError if anything prevents it
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from creating a new module. It may return None to indicate
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that the spec should create the new module.
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create_module() is optional.
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"""
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# By default, defer to default semantics for the new module.
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return None
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# We don't define exec_module() here since that would break
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# hasattr checks we do to support backward compatibility.
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def load_module(self, fullname):
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"""Return the loaded module.
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The module must be added to sys.modules and have import-related
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attributes set properly. The fullname is a str.
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ImportError is raised on failure.
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This method is deprecated in favor of loader.exec_module(). If
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exec_module() exists then it is used to provide a backwards-compatible
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functionality for this method.
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"""
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if not hasattr(self, 'exec_module'):
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raise ImportError
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return _bootstrap._load_module_shim(self, fullname)
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def module_repr(self, module):
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"""Return a module's repr.
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Used by the module type when the method does not raise
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NotImplementedError.
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This method is deprecated.
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"""
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# The exception will cause ModuleType.__repr__ to ignore this method.
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raise NotImplementedError
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class ResourceLoader(Loader):
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"""Abstract base class for loaders which can return data from their
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back-end storage.
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This ABC represents one of the optional protocols specified by PEP 302.
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"""
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@abc.abstractmethod
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def get_data(self, path):
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"""Abstract method which when implemented should return the bytes for
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the specified path. The path must be a str."""
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raise IOError
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class InspectLoader(Loader):
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"""Abstract base class for loaders which support inspection about the
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modules they can load.
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This ABC represents one of the optional protocols specified by PEP 302.
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"""
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def is_package(self, fullname):
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"""Optional method which when implemented should return whether the
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module is a package. The fullname is a str. Returns a bool.
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Raises ImportError if the module cannot be found.
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"""
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raise ImportError
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def get_code(self, fullname):
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"""Method which returns the code object for the module.
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The fullname is a str. Returns a types.CodeType if possible, else
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returns None if a code object does not make sense
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(e.g. built-in module). Raises ImportError if the module cannot be
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found.
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"""
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source = self.get_source(fullname)
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if source is None:
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return None
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return self.source_to_code(source)
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@abc.abstractmethod
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def get_source(self, fullname):
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"""Abstract method which should return the source code for the
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module. The fullname is a str. Returns a str.
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Raises ImportError if the module cannot be found.
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"""
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raise ImportError
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@staticmethod
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def source_to_code(data, path='<string>'):
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"""Compile 'data' into a code object.
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The 'data' argument can be anything that compile() can handle. The'path'
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argument should be where the data was retrieved (when applicable)."""
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return compile(data, path, 'exec', dont_inherit=True)
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exec_module = _bootstrap._LoaderBasics.exec_module
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load_module = _bootstrap._LoaderBasics.load_module
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_register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter)
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class ExecutionLoader(InspectLoader):
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"""Abstract base class for loaders that wish to support the execution of
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modules as scripts.
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This ABC represents one of the optional protocols specified in PEP 302.
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"""
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@abc.abstractmethod
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def get_filename(self, fullname):
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"""Abstract method which should return the value that __file__ is to be
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set to.
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Raises ImportError if the module cannot be found.
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"""
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raise ImportError
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def get_code(self, fullname):
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"""Method to return the code object for fullname.
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Should return None if not applicable (e.g. built-in module).
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Raise ImportError if the module cannot be found.
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"""
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source = self.get_source(fullname)
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if source is None:
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return None
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try:
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path = self.get_filename(fullname)
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except ImportError:
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return self.source_to_code(source)
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else:
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return self.source_to_code(source, path)
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_register(ExecutionLoader, machinery.ExtensionFileLoader)
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class FileLoader(_bootstrap.FileLoader, ResourceLoader, ExecutionLoader):
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"""Abstract base class partially implementing the ResourceLoader and
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ExecutionLoader ABCs."""
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_register(FileLoader, machinery.SourceFileLoader,
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machinery.SourcelessFileLoader)
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class SourceLoader(_bootstrap.SourceLoader, ResourceLoader, ExecutionLoader):
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"""Abstract base class for loading source code (and optionally any
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corresponding bytecode).
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To support loading from source code, the abstractmethods inherited from
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ResourceLoader and ExecutionLoader need to be implemented. To also support
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loading from bytecode, the optional methods specified directly by this ABC
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is required.
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Inherited abstractmethods not implemented in this ABC:
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* ResourceLoader.get_data
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* ExecutionLoader.get_filename
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"""
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def path_mtime(self, path):
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"""Return the (int) modification time for the path (str)."""
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if self.path_stats.__func__ is SourceLoader.path_stats:
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raise IOError
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return int(self.path_stats(path)['mtime'])
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def path_stats(self, path):
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"""Return a metadata dict for the source pointed to by the path (str).
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Possible keys:
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- 'mtime' (mandatory) is the numeric timestamp of last source
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code modification;
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- 'size' (optional) is the size in bytes of the source code.
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"""
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if self.path_mtime.__func__ is SourceLoader.path_mtime:
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raise IOError
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return {'mtime': self.path_mtime(path)}
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def set_data(self, path, data):
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"""Write the bytes to the path (if possible).
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Accepts a str path and data as bytes.
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Any needed intermediary directories are to be created. If for some
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reason the file cannot be written because of permissions, fail
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silently.
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"""
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_register(SourceLoader, machinery.SourceFileLoader)
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